The final design of the Korea Aerospace Industries KF-X fighter is expected in June 2018, at which point detailed design will commence.
The detailed design phase for the twin-engined type will run until late 2019, at which point the production of prototypes will commence, says an official familiar with the programme.
A first flight is planned in the middle part of 2022, with testing and evaluation to run until 2026.
The KF-X will have both single and two-seat versions, and be powered by two General Electric F414 engines.
At present, the design is undergoing wind tunnel tests and computational fluid dynamic analysis.
The official adds that Indonesia, which is undertaking 20% of development costs, obtained export licences from the US government in April 2017. Indonesian Aerospace has over 80 staff working on the programme, along with staff from Lockheed Martin and KAI. Jakarta's variant, of which it will obtain about 80 examples, is referred to as the IF-X.
"At this point, there is almost no difference between KF-X and IF-X shapes," says the official.
Still, the South Korean and Indonesian examples are likely to be different. Previously, officials have said that a Block I configuration without stealth coatings and the ability to carry weapons internally will go to Indonesia. South Korea will have a Block II aircraft, with stealth coatings and weapons bays.
Seoul will also develop indigenous capabilities in key areas where it failed to obtain export licences from the US, an early stumbling block for the programme. These include the jet's active electronically scanned array (AESA), which will be developed with Israeli assistance, infrared search & track (IRST), electro-optical targeting, and the aircraft's electronic warfare suite.
Seoul plans to obtain 80 IF-X fighters, while Seoul plans to obtain 120 examples of KF-X.